What constitutes discovery?

The experience of writing fiction or making art often entails the feeling of having made a discovery or realisation. For fiction writers, this realisation can inspire the revision of the manuscript. It can feel momentous, as though the change to the manuscript needs to be made, or the manuscript is flawed and needs to be amended. At the same time, such a discovery may feel as if it cannot be communicated, or can only be communicated to other writers.